The present invention relates to semiconductor devices and, more particularly, to a method and apparatus for protecting a semiconductor device.
FIG. 5 illustrates a conventional chip package 300. Typically, as shown in FIG. 5, the active surface 325 of a memory die 305 is flip chip attached to a chip-carrier 310 formed from printed circuit laminates. The inactive surface 320 of the memory die 305 is exposed and, thus, prone to handling-induced damage. The inactive surface 320 does not include interconnections to electrically couple the memory die 305 to other components. The active surface 325 of the memory die 305 is coupled to the chip carrier 310 by a C4 array 315 (i.e., an array of solder interconnections). The active surface 325 includes interconnections to be electrically coupled to other components.
The memory die 305 has a very low thermal coefficient of expansion while the chip carrier 310 has a very high thermal coefficient of expansion. As a result, after the memory die 305 has been coupled to the chip carrier 310 and allowed to cool to room temperature, the memory die 305 bends so that the center of the memory die 305 moves away from,the chip carrier 310 in the direction of arrow A1. The peripheral area of the memory die 305 moves towards the chip carrier 310 in the direction of arrows A2. Consequently, the memory die 305 deflects, causing the memory die 305 to have an arcuate shape. This creates a large amount of shear between the memory die 305 and the chip carrier 310 which may cause the C4 array 315 to fail.
To prevent the C4 array 315 from failing, an expoxy 330 is applied between the chip carrier 310 and the memory die 305. As a result, the memory die 305 and the chip carrier 310 are more strongly coupled together. Thus, the memory die 305 is further deflected, causing the inactive surface 320 of the memory die 305 to be under tension. If there are flaws in the inactive surface 320, the memory die 305 may fracture. Typically, flaws in the inactive surface 320 of the die occur from pick-and-place machines used to move the memory die 305 or from handling of the memory die 305. Inadvertent nicks and scratches on the memory die 305 can cause the flaws which result in incipient die cracking and, ultimately, catastrophic function failure of memory die 305.
Thus, it is an object of the present invention to prevent the die from being damaged. It is a further object of the present invention to protect the die without exerting further forces on the die that could cause the die to fail.
To achieve these and other objects, and in view of its purposes, the present invention provides a chip package that includes a die having an active surface and an inactive surface. An adhesive is formed on the inactive surface where the adhesive has a low Young""s modulus of elasticity. The low Young""s modulus of elasticity may be 10,000 psi or less, or 1,000 psi or less. Further, the adhesive may include a thermal conducting material. A protective plate is disposed on the inactive surface using the adhesive and a chip carrier is coupled to the active surface of the die.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention.